Leucocytoclastic vasculitis following influenza vaccination.

BACKGROUND: Influenza vaccinations are commonly administered and effectively prevent influenza. Most vaccine reactions are mild and self-limiting with few reported cases of vasculitis. We present a case of vasculitis post-vaccination unique for its dramatic visual presentation and rapid response to treatment with the aim to emphasise possible causation and timely treatment. CASE PRESENTATION: This is a case of a 60-year-old man with chronic idiopathic pulmonary fibrosis, with fever, arthralgias and rash characterised by extensive erythematous plaques on his limbs and trunk 5 days after influenza vaccination. Skin biopsy revealed leucocytoclastic vasculitis. Rash and symptoms resolved 10 days after initiating treatment with oral prednisone. CONCLUSIONS: Influenza vaccines can potentially precipitate cutaneous vasculitis, and timely treatment reduces morbidity in the elderly.

J-shapedness: an often missed, often miscalculated relation: the example of weight and mortality.

We present three considerations in analysing the association between weight and mortality, as well as other relations that might be non-linear in nature. First, authors must graphically plot their independent and dependent variables in a continuous manner. Second, authors should assess the shape of that relation, and note its shape. If it is non-linear, and specifically, J-shaped or U-shaped, careful consideration should be given to using the 'best' statistical model, of which multivariate fractional polynomial regression is a reasonable choice. Authors should also refrain from truncating their data to avoid dealing with non-linear relations.